ginac/relational.cpp

   1 /** @file relational.cpp
   2  *
   3  *  Implementation of relations between expressions */
   4
   5 /*
   6  *  GiNaC Copyright (C) 1999-2002 Johannes Gutenberg University Mainz, Germany
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software
  20  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  */
  22
  23 #include <iostream>
  24 #include <stdexcept>
  25
  26 #include "relational.h"
  27 #include "numeric.h"
  28 #include "print.h"
  29 #include "archive.h"
  30 #include "utils.h"
  31
  32 namespace GiNaC {
  33
  34 GINAC_IMPLEMENT_REGISTERED_CLASS(relational, basic)
  35
  36 //////////
  37 // default ctor, dtor, copy ctor, assignment operator and helpers
  38 //////////
  39
  40 relational::relational() : basic(TINFO_relational) {}
  41
  42 void relational::copy(const relational & other)
  43 {
  44         basic::copy(other);
  45         lh=other.lh;
  46         rh=other.rh;
  47         o=other.o;
  48 }
  49
  50 DEFAULT_DESTROY(relational)
  51
  52 //////////
  53 // other ctors
  54 //////////
  55
  56 // public
  57
  58 relational::relational(const ex & lhs, const ex & rhs, operators oper) : basic(TINFO_relational), lh(lhs), rh(rhs), o(oper) {}
  59
  60 //////////
  61 // archiving
  62 //////////
  63
  64 relational::relational(const archive_node &n, const lst &sym_lst) : inherited(n, sym_lst)
  65 {
  66         unsigned int opi;
  67         if (!(n.find_unsigned("op", opi)))
  68                 throw (std::runtime_error("unknown relational operator in archive"));
  69         o = (operators)opi;
  70         n.find_ex("lh", lh, sym_lst);
  71         n.find_ex("rh", rh, sym_lst);
  72 }
  73
  74 void relational::archive(archive_node &n) const
  75 {
  76         inherited::archive(n);
  77         n.add_ex("lh", lh);
  78         n.add_ex("rh", rh);
  79         n.add_unsigned("op", o);
  80 }
  81
  82 DEFAULT_UNARCHIVE(relational)
  83
  84 //////////
  85 // functions overriding virtual functions from base classes
  86 //////////
  87
  88 // public
  89
  90 void relational::print(const print_context & c, unsigned level) const
  91 {
  92         if (is_a<print_tree>(c)) {
  93
  94                 inherited::print(c, level);
  95
  96         } else {
  97
  98                 if (is_a<print_python_repr>(c)) {
  99                         c.s << class_name() << '(';
 100                         lh.print(c);
 101                         c.s << ',';
 102                         rh.print(c);
 103                         c.s << ",'";
 104                 } else {
 105                         if (precedence() <= level)
 106                                 c.s << "(";
 107                         lh.print(c, precedence());
 108                 }
 109                 switch (o) {
 110                         case equal:
 111                                 c.s << "==";
 112                                 break;
 113                         case not_equal:
 114                                 c.s << "!=";
 115                                 break;
 116                         case less:
 117                                 c.s << "<";
 118                                 break;
 119                         case less_or_equal:
 120                                 c.s << "<=";
 121                                 break;
 122                         case greater:
 123                                 c.s << ">";
 124                                 break;
 125                         case greater_or_equal:
 126                                 c.s << ">=";
 127                                 break;
 128                         default:
 129                                 c.s << "(INVALID RELATIONAL OPERATOR)";
 130                 }
 131                 if (is_a<print_python_repr>(c))
 132                         c.s << "')";
 133                 else {
 134                         rh.print(c, precedence());
 135                         if (precedence() <= level)
 136                                 c.s << ")";
 137                 }
 138         }
 139 }
 140
 141 bool relational::info(unsigned inf) const
 142 {
 143         switch (inf) {
 144                 case info_flags::relation:
 145                         return 1;
 146                 case info_flags::relation_equal:
 147                         return o==equal;
 148                 case info_flags::relation_not_equal:
 149                         return o==not_equal;
 150                 case info_flags::relation_less:
 151                         return o==less;
 152                 case info_flags::relation_less_or_equal:
 153                         return o==less_or_equal;
 154                 case info_flags::relation_greater:
 155                         return o==greater;
 156                 case info_flags::relation_greater_or_equal:
 157                         return o==greater_or_equal;
 158         }
 159         return 0;
 160 }
 161
 162 unsigned relational::nops() const
 163 {
 164         return 2;
 165 }
 166
 167 ex & relational::let_op(int i)
 168 {
 169         GINAC_ASSERT(i>=0);
 170         GINAC_ASSERT(i<2);
 171
 172         return i==0 ? lh : rh;
 173 }
 174
 175 ex relational::eval(int level) const
 176 {
 177         if (level==1)
 178                 return this->hold();
 179
 180         if (level == -max_recursion_level)
 181                 throw(std::runtime_error("max recursion level reached"));
 182
 183         return (new relational(lh.eval(level-1),rh.eval(level-1),o))->setflag(status_flags::dynallocated | status_flags::evaluated);
 184 }
 185
 186 ex relational::simplify_ncmul(const exvector & v) const
 187 {
 188         return lh.simplify_ncmul(v);
 189 }
 190
 191 // protected
 192
 193 int relational::compare_same_type(const basic & other) const
 194 {
 195         GINAC_ASSERT(is_exactly_a<relational>(other));
 196         const relational &oth = static_cast<const relational &>(other);
 197         if (o==oth.o && lh.is_equal(oth.lh) && rh.is_equal(oth.rh))
 198                 return 0;
 199         switch (o) {
 200                 case equal:
 201                 case not_equal:
 202                         if (oth.o!=o)
 203                                 return (o < oth.o) ? -1 : 1;
 204                         break;
 205                 case less:
 206                         if (oth.o!=greater)
 207                                 return (o < oth.o) ? -1 : 1;
 208                         break;
 209                 case less_or_equal:
 210                         if (oth.o!=greater_or_equal)
 211                                 return (o < oth.o) ? -1 : 1;
 212                         break;
 213                 case greater:
 214                         if (oth.o!=less)
 215                                 return (o < oth.o) ? -1 : 1;
 216                         break;
 217                 case greater_or_equal:
 218                         if (oth.o!=less_or_equal)
 219                                 return (o < oth.o) ? -1 : 1;
 220                         break;
 221         }
 222         const int lcmpval = lh.compare(oth.rh);
 223         return (lcmpval!=0) ? lcmpval : rh.compare(oth.lh);
 224 }
 225
 226 bool relational::match_same_type(const basic & other) const
 227 {
 228         GINAC_ASSERT(is_exactly_a<relational>(other));
 229         const relational &oth = static_cast<const relational &>(other);
 230
 231         return o == oth.o;
 232 }
 233
 234 unsigned relational::return_type(void) const
 235 {
 236         GINAC_ASSERT(lh.return_type()==rh.return_type());
 237         return lh.return_type();
 238 }
 239
 240 unsigned relational::return_type_tinfo(void) const
 241 {
 242         GINAC_ASSERT(lh.return_type_tinfo()==rh.return_type_tinfo());
 243         return lh.return_type_tinfo();
 244 }
 245
 246 unsigned relational::calchash(void) const
 247 {
 248         unsigned v = golden_ratio_hash(tinfo());
 249         unsigned lhash = lh.gethash();
 250         unsigned rhash = rh.gethash();
 251
 252         v = rotate_left_31(v);
 253         switch(o) {
 254                 case equal:
 255                 case not_equal:
 256                         if (lhash>rhash) {
 257                                 v ^= lhash;
 258                                 lhash = rhash;
 259                         } else {
 260                                 v ^= rhash;
 261                         }
 262                         break;
 263                 case less:
 264                 case less_or_equal:
 265                         v ^= rhash;
 266                         break;
 267                 case greater:
 268                 case greater_or_equal:
 269                         v ^= lhash;
 270                         lhash = rhash;
 271                         break;
 272         }
 273         v = rotate_left_31(v);
 274         v ^= lhash;
 275
 276         // mask out numeric hashes:
 277         v &= 0x7FFFFFFFU;
 278
 279         // store calculated hash value only if object is already evaluated
 280         if (flags & status_flags::evaluated) {
 281                 setflag(status_flags::hash_calculated);
 282                 hashvalue = v;
 283         }
 284
 285         return v;
 286 }
 287
 288 //////////
 289 // new virtual functions which can be overridden by derived classes
 290 //////////
 291
 292 /** Left hand side of relational. */
 293 ex relational::lhs(void) const
 294 {
 295         return lh;
 296 }
 297
 298 /** Right hand side of relational. */
 299 ex relational::rhs(void) const
 300 {
 301         return rh;
 302 }
 303
 304 //////////
 305 // non-virtual functions in this class
 306 //////////
 307
 308 /** Cast the relational into a boolean, mainly for evaluation within an
 309  *  if-statement.  Note that (a<b) == false does not imply (a>=b) == true in
 310  *  the general symbolic case.  A false result means the comparison is either
 311  *  false or undecidable (except of course for !=, where true means either
 312  *  unequal or undecidable). */
 313 relational::operator bool() const
 314 {
 315         const ex df = lh-rh;
 316         if (!is_ex_exactly_of_type(df,numeric))
 317                 // cannot decide on non-numerical results
 318                 return o==not_equal ? true : false;
 319
 320         switch (o) {
 321                 case equal:
 322                         return ex_to<numeric>(df).is_zero();
 323                 case not_equal:
 324                         return !ex_to<numeric>(df).is_zero();
 325                 case less:
 326                         return ex_to<numeric>(df)<_num0;
 327                 case less_or_equal:
 328                         return ex_to<numeric>(df)<=_num0;
 329                 case greater:
 330                         return ex_to<numeric>(df)>_num0;
 331                 case greater_or_equal:
 332                         return ex_to<numeric>(df)>=_num0;
 333                 default:
 334                         throw(std::logic_error("invalid relational operator"));
 335         }
 336 }
 337
 338 } // namespace GiNaC